Plastic wheels or runners



July 2, 1963 o. KIEFER PLASTIC WHEELS OR RUNNERS Filed Nov. 3. 1960 "Hut R OR ME EF WE m 0 T T O United States Patent 3,095,822 PLASTIC WIEELSOR RUNNERS Otto Kiefer, 89 Schottstrasse, Stuttgart, Germany Filed Nov.3, 1960, Ser. No. 67,108 Claims priority, application Germany Apr. 1,1960 1 Ciaim. (Cl. 103-414) The invention described herein relates tothe construction of integrally formed non-metallic impellers and themethod of forming such impellers.

More specifically the invention is directed to an improved thermoplasticmaterial impeller of the type generally used in centrifugal fans orpumps.

In prior art devices of this nature the usual impeller is constructedfrom a plurality of difierent parts. Ordinarily a hub and base aremachined or cast from metal and then a plurality of circumferentiallyspaced vanes or paddles are welded on or afiixed to the base and/ or hubin some manner. Other metal impellers have been constructed wherein thevanes were integrally formed with the base. In either case the impellerwas rather heavy and unsuitable for use where weight was aconsideration.

In order to meet the present day demands for a relatively light weightimpeller subsequent improvements were made. At present lighter weightimpellers are usually constructed from plastic and metal parts or solelyfrom plastic.

Impellers constructed from a combination of plastic and metal componentshave several inherent disadvantages. First, separate operations arerequired to form the different parts, and second the subsequent assemblyof these parts involves additional labor. Another disadvantage is thatthe parts being mechanically joined together are more subject to failurethan the parts in an integrally formed impeller.

In constructing impellers formed solely from plastic, a quantity offluid plastic material is injected into a mold and allowed to harden.The result is a rotor having a fair degree of rigidity and strength.However, as the prior art discloses, in order to have strength andrigidity, plastic impellers are solid in construction. This constructionrequires a considerable amount of plastic material to form the impeller,also a relatively complicated apparatus is necessary to perform themolding operation.

An object of the present invention is to overcome the disadvantages ofthe prior art devices by constructing an improved non-metallic impellerhaving integrally formed hollow vanes or paddles.

Another object of this invention is an improved nonmetallic impellerwith hollow vanes having side walls diverging from their apex to thebase affording considerable strength and rigidity.

Another object of the invention is an improved nonmetallic impellerhaving its connection to the shaft at the center of gravity of thewheel.

Another object of the invention is an improved nonmetallic impellerwhich is very light in weight, and economical to manufacture.

Another object of the invention is an improved method of formingnon-metallic impellers or the like.

Other objects and advantages of this invention will be readilyappreciated by reference to the following detailed description whenconsidered in connection with the accompanyin g drawings wherein:

FIGURE 1 is a top plan view showing the completed impeller and theposition of the blades with respect to the base and hub.

FIGURE 2 is a bottom plan view of the impeller showing the openings inits underside which define the hollow areas of the vanes.

FIGURE 3 is a side elevation of FIGURE 1 with parts 3,095,822 PatentedJuly 2, 1963 in section showing the extended hub portion and theintegral construction of one of the hollow vanes.

FIGURE 4 is an enlarged cross section of one of the vanes showing thehollow construction and the upwardly converging side walls. In dottedline is shown a portion of the mold in which the impeller is formed. Theimpeller can be formed also by a positive model which has the advantageof being cheaper and less heavy.

FIGURE 5 is similar to FIGURE 4 showing an alternate type of mold indotted lines.

FIGURE 1 shows an impeller 10 which has a plurality of circumferentiallyspaced hollow vanes 12 project-ing upwardly from a base member .14. Ahub 16 through which a power shaft, not shown, passes is centrallylocated in the base member 14.

In FIGURE 2 there is shown the underside of the impeller 10. Theopenings 20 in the base member 14 are the cavities in the hollow vanes12.

As shown in FIGURE '3, the hub 16 projects upwardly from the base member14 in the same direction as the vanes 12. The hollow vanes 12 are shownas extending radially outwardly from the hub 16, to a point adjacent theouter peripheral edge 18 of the base member 14.

The hub 16 is projected upwardly from the base 14 to the center ofgravity of the impeller 10 which is between the upper edges of the vanes12 and the base member .14. By forming the hub in this manner there willbe relatively no deformation or flexing of the impeller at highrevolutions. Also shown in FIGURE 2 is a side elevation in cross sectionof one of the hollow vanes 12. The vanes as shown are integrally formedwith the hub 16 and the base member 14.

FIGURE 4 illustrates one of the hollow vanes 12 in cross section showingthe continuous walls 22, and 24. The walls '22 and 24 converge upwardlyfrom the base member 14 to a rounded apex 26. By forming the vanes 12substantially V-shaped they will have the necessary strength andrigidity to resist the centrifugal force developed during rotation athigh speed and also resist the pressure of the fluid being moved.

In dotted lines there is shown a portion of the mold 28 in which theimpeller 10 is formed. The mold 28 has a plurality of cavities 30, oneof which is shown, corresponding in number to the number of vanes whichare to be formed on the impeller. There are also portions of the mold(not shown) wherein the base member and hub portion are formed. Informing the impeller a sheet of thermoplastic material is positioned inmold 28. The thermoplastic material is heated in order to soften it to aworkable state and it is then subjected to a molding pressuredifferential. This causes the softened thermo plastic sheet to conformto the configuration defined by the interior wall surfaces of the moldi.e., the plastic will be drawn or forced into the mold cavities formingthe hollow vanes 12, integral base member 14, and hub 16.

Referring to FIGURE 5 there is shown in dotted lines an alternate typeof mold 32 which can be used to form the impeller. In this instance, themold rather than being provided with a plurality of cavities has apositive configuration. The thermoplastic material when softened andsubjected to a molding pressure differential will be caused to conformto the mold surfaces. The resultant impeller will have a configurationas previously described.

The molding method used can be of either the vacuum or direct pressuretype with a negative or a positive model.

Although the invention has been described in its preferred form, it isto be understood that it is not limited to the details of constructionas shown as many modifications will be readily apparent to those skilledin the art, and all such modifications are to be considered within thescope and spirit of the appended claims.

What is claimed is:

An impeller unitary in structure and composed Wholly of thermoplasticmaterial, including a base member having an integral centrally locatedportion forming a hub, and having integral wall members extendingupwardly from said base member, said Wall members converging at theirtops to form a plurality of substantially V-shaped circumferentiallyspaced hollow vanes opening downwardly through said base member, saidvanes extending from a point adjacent the periphery of said base memberto said hub, and said hub extending upwardly from said base member tothe vertical center of gravity of said impeller between the upper edgeof said vanes and said base member.

References Cited in the file of this patent UNITED STATES PATENTS1,688,001 Altorfer Oct. 16, 1928 4 Dietenberger May 14, 19 29 Jnengst eta1 Mar. 1, 1932 Bitterli et al Dec. 9, 1952 Kelly May 29, 1956 WernertSept. 25, 1956 Chubbuck Feb. 26, 1957 Smith et a1 Ian. 20, 1959 SettleFeb. 13, 1962 FOREIGN PATENTS Great Britain June 11, 1952 Great BritainI an. 13, 1954 Italy Apr. 23, 1954 France Apr. 27, 1957 France Nov. 10,1958

